Screening of Human Gut Bacterial Culture Collection Identifies Species That Biotransform Quercetin into Metabolites with Anticancer Properties.

We previously demonstrated that flavonoid metabolites inhibit cancer cell proliferation through both CDK-dependent and -independent mechanisms. The existing evidence suggests that gut microbiota is capable of flavonoid biotransformation to generate bioactive metabolites including 2,4,6-trihydroxybenzoic acid (2,4,6-THBA), 3,4-dihydroxybenzoic acid (3,4-DHBA), 3,4,5-trihyroxybenzoic acid (3,4,5-THBA) and 3,4-dihydroxyphenylacetic acid (DOPAC). In this study, we screened 94 human gut bacterial species for their ability to biotransform flavonoid quercetin into different metabolites. We demonstrated that five of these species were able to degrade quercetin including Bacillus glycinifermentans, Flavonifractor plautii, Bacteroides eggerthii, Olsenella scatoligenes and Eubacterium eligens. Additional studies showed that B. glycinifermentans could generate 2,4,6-THBA and 3,4-DHBA from quercetin while F. plautii generates DOPAC. In addition to the differences in the metabolites produced, we also observed that the kinetics of quercetin degradation was different between B. glycinifermentans and F. plautii, suggesting that the pathways of degradation are likely different between these strains. Similar to the antiproliferative effects of 2,4,6-THBA and 3,4-DHBA demonstrated previously, DOPAC also inhibited colony formation ex vivo in the HCT-116 colon cancer cell line. Consistent with this, the bacterial culture supernatant of F. plautii also inhibited colony formation in this cell line. Thus, as F. plautii and B. glycinifermentans generate metabolites possessing antiproliferative activity, we suggest that these strains have the potential to be developed into probiotics to improve human gut health.

Bromo-dragonfly, a psychoactive benzodifuran, is resistant to hepatic metabolism and potently inhibits monoamine oxidase A.

Bromo-dragonfly is a benzodifuran derivative known as one of the most potent 5-HT2A-receptor agonists within this chemical class, with long-lasting effects of up to 2-3 days. In addition to hallucinogenic effects, the drug is a potent vasoconstrictor, resulting in severe adverse effects, such as necrosis of the limbs. In some cases, intoxication has had fatal outcomes. Little is known about the metabolism of bromo-dragonfly. The aims of this study were to investigate the pharmacokinetics of bromo-dragonfly, determine the plasma protein binding, examine the human hepatic metabolism in vitro, and compare with those of its close analogue, 2C-B-fly. Additionally, we assayed the inhibition potency of both compounds on the monoamine oxidase (MAO) A- and B-mediated oxidative deamination of serotonin (5-HT) and dopamine, respectively. Liquid chromatography high-resolution mass spectrometry was used for metabolism studies in pooled human liver microsomes (HLM), pooled human liver cytosol (HLC) and recombinant enzymes. Inhibition studies of the deamination of 5-HT and dopamine were carried out using LC-MS/MS. Bromo-dragonfly was not metabolised in the tested in vitro systems. On the other hand, 2C-B-fly was metabolised in HLM by CYP2D6 and in HLC to some extent, with the main biotransformations being monohydroxylation and N-acetylation. Furthermore, MAO-A metabolised 2C-B-fly, producing the aldehyde metabolite, which was trapped in vitro with methoxyamine. Inhibition experiments revealed that bromo-dragonfly is a competitive inhibitor of MAO-A with a Ki of 0.352 µM. The IC50 value for bromo-dragonfly indicated that the inhibition of MAO-A may be clinically relevant. However, more data are needed to estimate its impact on the increase of 5-HT in vivo.

Preventive and therapeutic effect of brozopine on stroke in Dahl Salt-sensitive hypertensive rats.

Our aim was to explore the preventive and therapeutic effects of sodium (±)-5-bromo-2-(α-hydroxypentyl) benzoate (brand name: brozopine, BZP) on stroke in Dahl Salt-sensitive (Dahl-SS) hypertensive rats. Dahl-SS rats were fed a high-salt diet to observe the effect of BZP on blood pressure, and brain, heart, and kidney tissues. Additionally, the incidence of stroke was recorded according to the neurological score. The relative mechanisms investigated included anti-oxidative effects and anti-platelet aggregation. BZP reduced the incidence of stroke, neuronal necrosis in the brain, and cell swelling and inflammatory infiltration in the kidney. Its mechanisms were related to the increased activities of gluthatione peroxidase and catalase and the decreased level of plasma nitric oxide. BZP inhibited arachidonic acid (AA) - induced platelet aggregation (IC50: 12µM) rather than that of adenosine diphosphate (ADP) - and/or thrombin-induced platelet aggregation in vitro. Interestingly, BZP inhibited ADP-, thrombin-, or AA-induced platelet aggregation and elevated the level of AMP-activated protein kinase, cyclic guanosine monophosphate, and vasodilator-stimulated-phosphoprotein, and attenuated ATP contents and mitogen-activated protein kinase levels in platelet and inhibited thrombus formation in a carotid artery thrombosis model, dose-dependently, in Dahl-SS hypertensive-induced stroke rats. In conclusion, BZP can have therapeutic and preventive effects on stroke in Dahl-SS hypertensive rats, the mechanisms of which may be related to anti-oxidant, anti-platelet aggregation and anti-thrombus formation.

Comparison of in vitro hormone activities of novel flame retardants TBB, TBPH and their metabolites TBBA and TBMEPH using reporter gene assays.

The anti-androgenic and anti-thyroid hormonal activities of the two novel brominated flame retardants, TBB and TBPH and of their metabolites TBBA and TBMEPH have been compared using the luciferase reporter gene assays. Only the parent compounds TBB and TBPH exhibited anti-glucocorticoid activity with IC50 values of 1.9 µM and 0.3 µM. Furthermore, mode of action for these two compounds is by direct competing to the glucocorticoid receptor (GR) with IC50 values of 0.03 µM and 0.002 µM. All four tested compounds possess anti-androgenic and anti-thyroid hormonal activities, without agonist activities on the respective receptors. Anti-androgenic activities with IC50 values of 43.5 µM, 0.1 µM, 47.5 µM and 1.3 µM were found for TBB, TBPH, TBBA and TBMEPH. The anti-thyroid hormonal IC50 values of 37.5 µM, 0.1 µM, 22.8 µM and 32.3 µM for TBB, TBPH, TBBA and TBMEPH, together with the above quoted results, indicate that metabolism can modify anti-androgenic, anti-glucocorticoid and anti-thyroid hormonal effects of these novel brominated flame retardants. Furthermore, the parent flame retardants are shown to be able to disrupt the function of the GR as antagonists by direct competition to the receptor.